Theoretical Modelling of Cascaded Er~(3+)-Doped,Tm~(3+)-Doped and Nd~(3+)-Doped Fibers for 0.4 to 2.0 μm Emission Spectra

We present a cascaded system designed with Er~(3+)-doped, Tm~(3+)-doped and Nd~(3+)-doped fibers to realize amplified spontaneous emission(ASE) spectra covering 0.4—2.0 μm. The system is excited with a pump laser emitting 808 nm photons with 500 m W pump power. The emission spectra of the cascaded system covering0.4—2.0 μm are realized with the Er~(3+), Tm~(3+)and Nd~(3+)ion doping densities optimized to 8 × 1019, 2 × 1020 and8 × 1020 ion/m3, respectively, and the fiber length optimized to 1 m. Numerical methods reveal that the peak ASE power for the cascaded system can reach 20.9 m W. A minimum ASE power of 4.39 m W is attainable. Using numerical calculations and analytical techniques, we provide a detailed insight into optimized Er~(3+)-doped, Tm~(3+)-doped and Nd~(3+)-doped fiber lengths and their doping concentrations for ASE power spectra covering 0.4—2.0 μm.We believe that the cascaded system can potentially provide significant applications in various optical fields which include but not limited to wavelength-division multiplexing, various optical communications and other salient medical imaging processes.